Process for the recovery of ammonia and other valuable chemicals from waste denitration liquors



Patented Apr. 15,1924,

UNITED STATES PATENT OFFICE.

EMILE smnscnnnnns, or jLANsnownn, PENNSYLVANIA; Assmxon' 'ro TUBIZE AmrrrcrAn sun: COMPANY or AMERICA, A conronA'rron or DELAWARE.

PROCESS FOR THE RECOVERY OF AMMONIA AN D OTHER VALULBLE CHEHIQALS FROM ilo v To all whom it may concern:

Be it known that I, EMILE Bmnsonnnnnn, -a c tizen of the Republic of Switzerland, residing in Lansdowne, county of Delaware,

5 in the State of Pennsylvania, have inventedcertain new and useful Improvements in Processes for the 'Reeovery of An'nnonia and Other Valuable Chemicals from Waste Denitration Liquors, of which the following is 10 a true and exact description.

M invention relates to the recovery of valuable chemicals from waste liquors, re-. sulting from the process of denitratmg'nitrocellulose silk with sodium 'sulfhydrate.

R5 These waste liquors contain sodium polysulphides, some unchanged sodium 'sulfhydrate and a small amount of thiosulphateas sulphur compounds, sodium nitrite and. ammonia as nitrogen compounds.

90 The object of'my inventlon is by a simple and inexpensive recess to recover from waste liquors resu ting from the denitration of nitrocellulose silk with sodium sulfhy: drate, ammonia and other valuable chemicals including, by preference, sodium sulfhydrate in condition to be used for denitration. I am aware that it has been proposed to treat waste liquors resultin from the de-" a nitration of nitrocellulose si by calcium sulfhydrate with carbonic acid whereby hydrogen sulphide gas is recovered from unchanged calcium 'sulfhydrate and to se arate from the remaining liquors nitrite an thiosulphate by concentration and fractional crystallization. I have discovered, however, that where carbon dioxide is used to treat waste liquors resulting from the denitration of nitrocellulose silk by sodium sulfhydrate the reactions proceed in an entirely difierent wa and that a larger recovery of ammonia is made possible, and primarily my invention consists in the process of treating the denitrated waste liquors resulting from the denitration by sodium sulfhydrate with carbon dioxide and the recovery of ammonia and other valuable chemicals from the waste liquor resulting from this treatment, by preference, ca as ereafter descri ed so as to recover sodium sulfhydrate incondition for reuse.

My process ma be describedas follows: 1 introduce into e waste liquors resultin from the denitration of nitrocellulose s' I by sodium sulfhydrate, which I first heat to WASTE nnnr'rnA'rlon mesons.

ing the process forward I V '7. NaOH+NaHS0 =Na,S0 +H,O- 8. Na SO +CaSO +8O=Na S+CaS+8C0 lpplieatlonoflled June 2, 1928. Serial Io, 643,086.

a temperature of from 6( to 80 0., carbon dioxide gas,,as a result of which practically no hydrogen sulphide gas is evolved but sulphur is, precipitated out and .the-

color of the liquor changes from dark red to a very light yellow.

The reaction which is preferably carried out at about 80 C. seems to roceed along the lines'as shown by the 0 owing equa tions with the ultimate result of a final conversion of the nitrite into ammonium carbonate, which upon treatment with milk of lime sets the ammonia free, which can be condensed or converted into ammonium sul-- cium carbonate, which is used to generate carbonic acid, by reaction with nitrecake or waste sulphuric acid,'the remaining mother liquor containin mostly caustic soda and some sodium thiosulphate is treated w th nitrecake to produce sodium sulphate, WhlCh upon filtering from some preclpitated sulphur, crystallizes out upon concentration and cooling of the liquor. The sodium sulphate and the calcium sulphate obtained accordrn to equations 6 and 7 can be reduced wit coal, according to well known methods, to a mixture of sodium sulphide and 08110111111 sulphide.- Upon leaching with water, the sodium sulphide enters 1n solution and 1s separated by filtration from the calcium sulhide and converted into sodium sulyghyrate by treating it with hydrogen sul ide gas generated from the calcium sulphi e by treatment with waste sulphuric acid or nltrecake equations 9 and 10) and the manufacture of sodium sulfhydratc, the materials used being only cheap or valueless by-products like nitre-cake and denitration waste liquors, the onl material to be purchased being coal, w e the chemicals obtained, ammonium sulphate and sulphur are of substantial value. p

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. Process for the treatment of waste li uors from denitration of nitrocellulose si with sodium sulfhydrate, which consists in heating said liquors, treating said heated liquors with carbonic acid, removing the su phur plrecipitated out, treating the remaming 'quor with lime, and driving off and recovering ammonia. g

2. Process for the treatment of waste li uors from denitration of nitrocellulose with sodium sulfhydrate, which consists in heating said liquors, treating said heated a liquors with carbonic acid, removing the sulphur precipitated out, treatin 'the remaining mother liquor to produce sodium sul-.

phate. r 3. Process for I the treatment of waste liquors from denitration of nitrocellulose silk with sodiumsulfhydrate, which consists inheating said liquors, treating said heated liquors with carbonic acid, removing the'sulmg liquor with lime, driving 0 and recovering ammonia, filtering the prec pitated calcium carbonate, treating the used for the carbonation of the waste liquors, adding nitrecake to the alkaline mother "EMILE BINDSOHEDLEB.

atter with I nitrecake to generate carbonic acid to be a 

